On 2021-05-11 2:38 a.m., Christian König wrote:
Am 10.05.21 um 18:36 schrieb Andrey Grodzovsky:
On device removal reroute all CPU mappings to dummy page.
v3:
Remove loop to find DRM file and instead access it
by vma->vm_file->private_data. Move dummy page installation
into a separate function.
v4:
Map the entire BOs VA space into on demand allocated dummy page
on the first fault for that BO.
v5: Remove duplicate return.
v6: Polish ttm_bo_vm_dummy_page, remove superflous code.
Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@xxxxxxx>
---
drivers/gpu/drm/ttm/ttm_bo_vm.c | 57 ++++++++++++++++++++++++++++++++-
include/drm/ttm/ttm_bo_api.h | 2 ++
2 files changed, 58 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c
b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index b31b18058965..e5a9615519d1 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -34,6 +34,8 @@
#include <drm/ttm/ttm_bo_driver.h>
#include <drm/ttm/ttm_placement.h>
#include <drm/drm_vma_manager.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_managed.h>
#include <linux/mm.h>
#include <linux/pfn_t.h>
#include <linux/rbtree.h>
@@ -380,19 +382,72 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct
vm_fault *vmf,
}
EXPORT_SYMBOL(ttm_bo_vm_fault_reserved);
+static void ttm_bo_release_dummy_page(struct drm_device *dev, void
*res)
+{
+ struct page *dummy_page = (struct page *)res;
+
+ __free_page(dummy_page);
+}
+
+vm_fault_t ttm_bo_vm_dummy_page(struct vm_fault *vmf, pgprot_t prot)
+{
+ struct vm_area_struct *vma = vmf->vma;
+ struct ttm_buffer_object *bo = vma->vm_private_data;
+ struct drm_device *ddev = bo->base.dev;
+ vm_fault_t ret = VM_FAULT_NOPAGE;
+ unsigned long address;
+ unsigned long pfn;
+ struct page *page;
+
+ /* Allocate new dummy page to map all the VA range in this VMA
to it*/
+ page = alloc_page(GFP_KERNEL | __GFP_ZERO);
+ if (!page)
+ return VM_FAULT_OOM;
+
+ pfn = page_to_pfn(page);
+
+ /* Prefault the entire VMA range right away to avoid further
faults */
+ for (address = vma->vm_start; address < vma->vm_end; address +=
PAGE_SIZE) {
+
+ if (unlikely(address >= vma->vm_end))
+ break;
That extra check can be removed as far as I can see.
+
+ if (vma->vm_flags & VM_MIXEDMAP)
+ ret = vmf_insert_mixed_prot(vma, address,
+ __pfn_to_pfn_t(pfn, PFN_DEV),
+ prot);
+ else
+ ret = vmf_insert_pfn_prot(vma, address, pfn, prot);
+ }
+
+ /* Set the page to be freed using drmm release action */
+ if (drmm_add_action_or_reset(ddev, ttm_bo_release_dummy_page,
page))
+ return VM_FAULT_OOM;
You should probably move that before inserting the page into the VMA
and also free the allocated page if it goes wrong.
drmm_add_action_or_reset will automatically release the page if the add
action fails, that the 'reset' part of the function.
Andrey
Apart from that patch looks good to me,
Christian.
+
+ return ret;
+}
+EXPORT_SYMBOL(ttm_bo_vm_dummy_page);
+
vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf)
{
struct vm_area_struct *vma = vmf->vma;
pgprot_t prot;
struct ttm_buffer_object *bo = vma->vm_private_data;
+ struct drm_device *ddev = bo->base.dev;
vm_fault_t ret;
+ int idx;
ret = ttm_bo_vm_reserve(bo, vmf);
if (ret)
return ret;
prot = vma->vm_page_prot;
- ret = ttm_bo_vm_fault_reserved(vmf, prot,
TTM_BO_VM_NUM_PREFAULT, 1);
+ if (drm_dev_enter(ddev, &idx)) {
+ ret = ttm_bo_vm_fault_reserved(vmf, prot,
TTM_BO_VM_NUM_PREFAULT, 1);
+ drm_dev_exit(idx);
+ } else {
+ ret = ttm_bo_vm_dummy_page(vmf, prot);
+ }
if (ret == VM_FAULT_RETRY && !(vmf->flags &
FAULT_FLAG_RETRY_NOWAIT))
return ret;
diff --git a/include/drm/ttm/ttm_bo_api.h
b/include/drm/ttm/ttm_bo_api.h
index 639521880c29..254ede97f8e3 100644
--- a/include/drm/ttm/ttm_bo_api.h
+++ b/include/drm/ttm/ttm_bo_api.h
@@ -620,4 +620,6 @@ int ttm_bo_vm_access(struct vm_area_struct *vma,
unsigned long addr,
void *buf, int len, int write);
bool ttm_bo_delayed_delete(struct ttm_device *bdev, bool remove_all);
+vm_fault_t ttm_bo_vm_dummy_page(struct vm_fault *vmf, pgprot_t prot);
+
#endif
